1. Field of the Invention
The present invention is generally relates to a system for mounting and testing printed circuit boards, and more specifically a system for aligning, retaining, connecting, terminating, and testing printed circuit boards.
2. Description of the Related Art
Most electronic devices today contain one or more Printed Circuit Boards (PCB). A PCB is used to mechanically support and electrically connect components of a device using conductive pathways called traces. For example, a computer usually contains a PCB called the motherboard. The motherboard contains the essential components of the computer such as the microprocessor and main memory, along with other basic components. The components may be housed in sockets and connected to each other using the traces.
During assembly of electronic devices, one or more PCBs may be secured to each other or to a device frame or chassis. Securing the PCBs usually involves fastening the PCB to another PCB, or to the device chassis, using screws. The PCB is usually secured on one or more standoffs. Placing the PCB on a standoff ensures airflow along both surfaces of the PCB, thereby allowing cooling during operation of the device. The standoffs also prevent undesired contact between active circuits of the PCB and other device components.
FIG. 1 illustrates the mounting of a PCB 110 on a chassis 120. Chassis 120 may contain one or more standoffs 121 on which the PCB may be mounted. As illustrated, standoffs 121 may be hollow cylindrical sleeves, the inner portion of the sleeve providing threading for fastening screws. During installation, the PCB is placed on the standoffs so that one or more apertures 112 of the PCB align with the one or more standoffs 121. A screw 111 may then be passed through each of the apertures 112 and secured to the standoffs 121 by means of the threaded inner sleeves of the standoffs.
One problem with the prior art is that the PCB installation can be quite laborious and time consuming. The PCB must first be aligned with the screw holes. The screws must then be tightened while keeping the PCB aligned with the screws. Maintaining alignment makes assembly slow and inefficient.
Screw installation requires additional tools and application of force to tighten the screws which may increase the risk of damage to sensitive components of the PCB. Furthermore, the screws are usually small and may be dropped on the PCB and other components or lost in the device, thereby increasing the risk of damage even further. Because screws are made of conductive materials, there is also a danger that the screws, if dropped in the device, may create undesired short circuits.
PCBs are also routinely subject to diagnostic testing prior to installation in a device. For example, the diagnostic testing may include connectivity testing to determine operating characteristics based on response of the PCB to imposed test signals. One or more connectors are typically attached to the PCB to facilitate testing. The connectors serve to connect one or more test cables that impose test signals on the PCB under test. For example, a connector 113 is shown in FIG. 1. FIG. 2 illustrates an enlarged bottom view of a PCB with a connector 113 and a standoff 121.
One problem with using prior art connectors is that testing can be time consuming and tedious. Typically, connectors serve to connect a single coaxial test cable to the PCB in order to perform a single testing function. Thus, when performing multiple tests, testing cables must be uncoupled from original connectors and re-coupled to other connectors. Alternatively, users may couple different testing cables to the same connector to perform other tests. However, this requires on-board logic to multiplex signals. The use of connectors and/or multiplexing logic may take up valuable space on the PCB. One skilled in the art will recognize that real estate on PCBs is precious given the increasing demand for greater functionality from smaller devices.
Yet another problem, as illustrated in FIG. 2, is that connectors are typically unsupported when mounted. Thus, the use of force when coupling cables to the connectors could crack or otherwise damage the PCB. Furthermore prior art connectors remain on the PCB after testing and even after the device is commercialized. Leaving connectors on the PCB can be very costly, especially given that some connectors may even be gold plated.
Therefore, what is needed is are improved methods, systems, and apparatus for efficient and safe installation and testing of PCBs.